For example, a machine tool is configured by: a table having a workpiece being mounted and fixed to its top surface by the jig for attaching the workpiece; a main spindle for retaining a tool; a drive mechanism for moving the table and the main spindle (workpiece and tool) relative to each other; a control device for controlling the drive mechanism based on an NC program previously created; and the like.
The NC program is created by an operator, a programming device, or the like. However, if there is an error, there is a possibility that an accident in which the tool and the workpiece or the jig for attaching the workpiece interfere with each other occurs. To avoid this, as disclosed in Japanese Unexamined Patent Application Publication No. 2006-004128, an interference simulation is conducted on a computer using three-dimensional model data of a machine tool to check whether the NC program has an error.    Patent document 1: Japanese Unexamined Patent Application Publication No. 2006-004128